IIOOSAC MOUNTAIN. 85 



entrance of Bowens creek into Tophet creek, a gently sloping bench con- 

 ceals all outcrops; then in Bowens creek we have Profile vm giving us a 

 typical section through this band of gneiss, the rock varying between a 

 vitreous quartzite, micaceous quartzite, and the hue grained gneiss typical 

 of this area. Above, the schist and then the eastern gneiss succeed the 

 first mentioned rocks. As will be seen in Profile vm the rocks have a 

 moderate easterly dip with few variations. 



The next exposure is on the north fork of Tophet creek, where this 

 scries begins a few feet below the lowest outcrop of the schist, and forms 

 a continuation of the canyon of the creek for over half a mile; the rock 

 makes great cliffs and bluffs with a well marked strike north 10° west and 

 a gentle dip of 10° to 15° east. Rock one hundred and fifty feet thick can 

 be seen; the south fork of Tophet creek shows the same; here the rocks 

 are much more quartzose — often a massive quartzite — and the dips are 

 irregular, in some cases northerly. 



Just below the junction of the two forks of Tophet creek the water 

 flows around the north end of an elliptical hill (Burlingames hill), the crest 

 of which is formed by a large outcrop of massive vitreous quartzite which 

 strikes north 10° east, dips 25° east. At the north end of the hill the creek 

 exposes outcrops of rock with the same strike, and an easterly dip of 15°, in 

 which a lenticular mass of massive quartzite passes into a dark feldspathic 

 biotite schist resembling the transitions between albite schist and gneiss. 

 The quartzite passes laterally as well as vertically into the schist, showing 

 the sudden transitions of which these rocks are capable. We have a broad 

 drift- covered area extending H miles from the outcrops of massive quartzite 

 on this hill to the limestone outcrops, and south to the schist in Cheshire; 

 an area which contains no outcrops whatever. From the south fork of 

 Tophet creek we get no outcrops of this band of gneiss until we get to 

 the "point" of the mountain. This locality is a large "canoe;" that is, 

 the strata turn suddenly from a north and south strike and easterly dip to 

 an east and west strike with northerly dip. We have described the schist 

 band and the manner in which it is overlain and underlain by white gneiss. 

 The underlying white gneisses corresponding to this western band occur in 

 great cliffs with a strike north 40° west and dip 15° to 20° north. From 



